phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 2

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('c4acb5229a936647c1c7146ba46e38f7', -1, 1464069525, 1464069525, '36a22d9d', -4, 0, 0)

Line : 188
File : sessions.php